US4197705A - Hydraulic control system - Google Patents
Hydraulic control system Download PDFInfo
- Publication number
- US4197705A US4197705A US05/910,726 US91072678A US4197705A US 4197705 A US4197705 A US 4197705A US 91072678 A US91072678 A US 91072678A US 4197705 A US4197705 A US 4197705A
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- US
- United States
- Prior art keywords
- control
- fluid
- displacement
- pump
- fluid communication
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
- F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
- F04B49/002—Hydraulic systems to change the pump delivery
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
- F15B2211/205—Systems with pumps
- F15B2211/2053—Type of pump
- F15B2211/20546—Type of pump variable capacity
- F15B2211/20553—Type of pump variable capacity with pilot circuit, e.g. for controlling a swash plate
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/305—Directional control characterised by the type of valves
- F15B2211/30505—Non-return valves, i.e. check valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/305—Directional control characterised by the type of valves
- F15B2211/30505—Non-return valves, i.e. check valves
- F15B2211/3051—Cross-check valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/31—Directional control characterised by the positions of the valve element
- F15B2211/3144—Directional control characterised by the positions of the valve element the positions being continuously variable, e.g. as realised by proportional valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/50—Pressure control
- F15B2211/505—Pressure control characterised by the type of pressure control means
- F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
- F15B2211/50518—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using pressure relief valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/50—Pressure control
- F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
- F15B2211/5151—Pressure control characterised by the connections of the pressure control means in the circuit being connected to a pressure source and a directional control valve
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/50—Pressure control
- F15B2211/55—Pressure control for limiting a pressure up to a maximum pressure, e.g. by using a pressure relief valve
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/605—Load sensing circuits
- F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
- F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
Definitions
- the present invention relates generally to a hydraulic control system for distributing fluid to a plurality of fluid actuated devices and more particularly to such a hydraulic control system for use with a variable displacement pump.
- variable displacement pumps have been used in combination with closed center control valves to achieve better system efficiency.
- the variable displacement pumps have been provided with pressure compensated controls.
- the pump idles at maximum system pressure.
- the control valve must meter down to the actual load pressure, which may provide a very large pressure drop across the valve. Such large pressure drops also result in a very inefficient use of energy.
- variable displacement pumps in combination with a closed center control valve have been utilized in a load sensitive system.
- a load sensitive system requires the use of a flow demand control valve for sensing the differential pressure between the pump inlet and some controlled point in the fluid supply to the load.
- load sensitive systems suffer from the disadvantage of being quite complex and therefore expensive to manufacture. Additionally, such load sensitive systems may be fooled in those circumstances where a load is being lowered with the aid of the force of gravity. Under these circumstances the load signal may reverse, resulting in diminished pump output rather than the desired increase in pump output.
- a hydraulic control system having a fluid reservoir, a variable displacement pump having a fluid input in fluid communication with the reservoir and having a fluid output, and a fluid actuated displacement control mechanism for controlling the displacement of the pump.
- a control valve is placed in fluid communication with the fluid output of the variable displacement pump and with the reservoir and is adapted to control the flow of fluid to a fluid actuated device.
- the control valve includes means for developing a control pressure signal.
- a sensor valve is placed in fluid communication with the control pressure signal, the displacement control mechanism, and the reservoir for placing the control pressure signal in fluid communication with the displacement control mechanism or for placing the displacement control mechanism in fluid communication with the reservoir, in response to the magnitude of the pressure control signal, thereby controlling the displacement of the pump in response to the magnitude of the pressure control signal.
- the control valve includes a plurality of plungers for controlling the flow of fluid between a central passageway, a supply manifold, service ports, and an exhaust manifold.
- Each of the plungers includes a plurality of metering notches for providing the only continuous flow path through the central passageway between the inlet and the exhaust port when the plungers are between a neutral position and an operating position.
- the fluid actuated displacement control mechanism is mechanically connected to the pump for controlling its displacement.
- the mechanism is provided with a fluid passage for placing the mechanism in fluid communication with the pump drain.
- the fluid passage includes a flow restriction which varies in response to the position of the mechanism.
- An object of the present invention is the provision of a hydraulic control system which is capable of controlling the distribution of fluid to a plurality of fluid actuated devices in a highly efficient and responsive manner.
- Another object of the present invention is the provision of a hydraulic control system for controlling the distribution of fluid to a plurality of fluid actuated devices which system is not subject to signal reversals as a result of gravitational forces acting on the fluid actuated devices.
- a further object of the present invention is the provision of a hydraulic control system for a variable displacement pump which requires the use of only a single control line to the pump.
- a further object of the present invention is the provision of a hydraulic control system for a variable displacement pump, including a control valve that develops a control pressure signal for the pump which is responsive to the position of individual valve plungers.
- Still another object of the present invention is the provision of a hydraulic control system for a variable displacement pump, including an improved displacement control mechanism for the pump.
- Yet another object of the present invention is the provision of a hydraulic control system for a variable displacement pump which may be easily manufactured by making relatively simple and inexpensive modifications to existing control systems.
- FIG. 1 is a graphic diagram of a first embodiment of the hydraulic control system of the present invention.
- FIG. 2 shows a front view in partial cross-section of a control valve suitable for use in the hydraulic control system shown in FIG. 1.
- FIG. 3 shows a partial cross-sectional view of a variable displacement pump suitable for use in the hydraulic control system shown in FIG. 1.
- FIG. 4 shows a schematic diagram of a sensor valve suitable for use in the hydraulic control system shown in FIG. 1.
- FIG. 5 shows a graphic diagram of a second embodiment of the hydraulic control system of the present invention.
- FIG. 6 shows a graphic diagram of a third embodiment of the hydraulic control system of the present invention.
- a hydraulic control system 10 is provided for controlling the distribution of fluid to a plurality of fluid actuated devices (not shown).
- a variable displacement pump has its fluid input in fluid communication with a reservoir 14.
- the pump 12 is provided with a fluid actuated displacement control mechanism 16 for controlling the displacement of the pump 12.
- a control valve 18 including a plurality of plungers 20 and 22 is placed in fluid communication with the fluid output of the variable displacement pump 12 and with the reservoir 14.
- the control valve 18 is adapted to control the flow of fluid to a plurality of fluid actuated devices (not shown) by connecting the devices to a plurality of service ports 24, 26, 28 and 30.
- Each of the plungers 20 and 22 includes a neutral position 32 and 34, respectively, in which fluid communication between the variable displacement pump 12 and the service ports 24, 26, 28 and 30 is blocked.
- Each of the plungers 20 and 22 also include a pair of operating positions 36 and 38, and 40 and 42, respectively, for placing the output of the variable displacement pump 12 in fluid communication with a service port.
- the control valve 18 further includes means for developing a control pressure signal including a fixed orifice 44 for restricting flow between the variable displacement pump 12 and the reservoir 14.
- Each of the plungers 20 and 22 further includes means graphically illustrated as variable orifices 46 and 48 respectively, for restricting flow in the flow path between the variable displacement pump 12 and the fixed orifice 44 when the plungers 20 and 22 are between their neutral positions 32 and 34 and one of their operating positions.
- the flow restricting means 46 and 48 provide a variable restriction in the flow path as the plungers 20 and 22 are moved from their neutral positions toward one of the operating positions.
- the control pressure signal is developed by positioning a control pressure port 50 between the flow restricting means 46 and the fixed orifice 44. The control pressure signal is then delivered along line 52 to a sensor valve 54.
- the sensor valve 54 is also in fluid communication with the displacement control mechanism 16 and the reservoir 14.
- the sensor valve 54 includes three operating positions.
- the sensor valve 54 is fluid biased by the control signal 52 toward a first operating position 56 in which the control pressure signal 52 is placed in fluid communication with the displacement control mechanism 16. Should the control pressure signal 52 apply a lower bias to the sensor valve 54 than a spring 58, the sensor valve 54 is spring biased into a second operating position 60 in which the displacement control mechanism 16 is placed in fluid communication with the reservoir 14. Should the control pressure signal bias equal the spring bias on the valve 54, the valve will be placed in a neutral position 62 for blocking fluid communication between the control signal 52, the displacement control mechanism 16, and the reservoir 14.
- each pair of service ports 24 and 28, and 26 and 30, respectively, is connected to a fluid actuated device (not shown).
- a fluid actuated device not shown
- the valve 18 is in its center or neutral position, as illustrated, and that a prime mover (not shown), provided for driving the pump 12, is started.
- the displacement control mechanism 16 is spring biased to full displacement so that the pump 12 is in stroke when it is started.
- the pump 12 thus delivers an output to the input port of the control valve 18.
- As much flow as possible passes through the restrictions 48 and 46 to the fixed orifice 44. A limited amount of flow then passes from the fixed orifice 44 to reservoir 14.
- valve plungers 20 and 22 are connected in a parallel configuration such that both plungers are always in fluid communication with the pump 12. Should the operator displace one of the plungers by a small amount so as to meter a relatively small amount of fluid to one of the service ports, the signal flow through restrictions 48 and 46 is reduced. This reduced flow generates a lower pressure at port 50 which in turn reduces the control signal pressure bias applied to valve 54. When the control signal bias drops below that applied in the opposite direction by spring 58, the sensor valve 54 shifts to position 60 permitting flow from the displacement control mechanism 16 to reservoir 14. The spring bias of the displacement control mechanism 16 will increase the displacement of pump 12 until the pressure build up at port 50 is sufficient to fluid bias valve 54 out of position 60. Thus, should the operator meter a small amount of fluid to a fluid actuated device, pump displacement will increase to an amount intermediate minimum and maximum flow until an equilibrium condition is reached.
- FIG. 2 shows a control valve for use in the hydraulic control system shown in FIG. 1.
- a control valve 18 includes an inlet port 70 adapted to be connected to the output of pump 12 and an exhaust port in fluid communication with an exhaust manifold 72 and reservoir 14.
- the valve 18 further includes a plurality of service ports 24 and 28, and 26 and 30 for delivering fluids to a fluid actuated device (not shown).
- the valve 18 further includes a plurality of generally cylindrical plungers 20 and 22 having an outer surface extending substantially symmetrically about longitudinal axis 76 and 78 respectively. Each of the plungers 20 and 22 includes a neutral position in which fluid communication between the supply manifold 74 and the service ports is blocked.
- Each of the plungers 20 and 22 further includes a pair of operating positions wherein a service port is placed in fluid communication with the supply manifold 74. This is accomplished by means of a plurality of pairs of radial ports 80 and 82 on plunger 20 and 84 and 86 on plunger 22. Each pair of ports includes an interconnecting closed axial bore placing the pair of ports in fluid communication with one another.
- Each of the plungers 20 and 22 includes a plurality of metering notches 90 for providing the only continuous flow path to the supply manifold between the inlet and the exhaust port when the plungers are between their neutral position and an operating position. These metering notches 90 make up the variable flow restrictions 46 and 48 shown in FIG. 1.
- Each of the plungers 20 and 22 further includes a recessed portion 91 positioned so as to be centered within a central passageway 92 when the plungers are in their neutral position. The recessed portions 91 are of sufficient depth so that they present no significant restriction to flow through the passageway 92 when the plungers are exactly in their neutral positions.
- the recessed portions 91 are in fluid communication with metering notches 90 and have a sufficiently small axial dimension so as to cooperate with the valve lands 93 to prevent direct flow through the recessed portions 91 when a given plunger is moved away from its neutral position a small axial distance and force all flow through metering notches 90.
- the axial dimension of the portions 91 is much smaller than the axial dimension of similar portions of standard parallel control valves. Thus it is apparent that the axial dimension of each portion 91 is only slightly greater than the width of lands 93.
- Each of the metering notches comprises a narrow channel in the outer surface of the plunger extending parallel to the longitudinal axis of the plunger. It is apparent from the structure of these notches that as a plunger is moved from the neutral position toward one of the operating positions direct flow through the recessed portion 91 will soon be prevented by land 93 and all flow through portion 91 and passageway 92 must utilize the metering notches 90. Thus as the plunger approaches an operating position, the amount of flow permitted to proceed upstream of that plunger along the central passageway 92 of the valve will be gradually reduced and eventually stopped. Although four such metering notches 90 are illustrated on each valve plunger, it should be understood, that a greater or lesser number could be provided as long as the hydrostatic balance of the valve plunger were not adversely affected.
- the valve 18 further includes the fixed orifice 44 positioned at the end of the central passageway 92 as was illustrated in FIG. 1. Additional orifices 94 and 96 may be provided in the exhaust manifold 72 and may even be sized so as to eliminate the need for orifice 44.
- the orifice 44 is, of course, positioned downstream of the last plunger and the control pressure port 50 is positioned in the central core downstream of the plungers but upstream of the orifice 44.
- FIG. 3 shows a variable displacement axial piston pump suitable for use with the control system of the present invention.
- the pump 12 includes a housing 100, inlet and outlet ports (not shown), and a drain (not shown) adapted to permit the return of excess fluid to reservoir 14.
- a drive shaft 102 positioned within the housing 100 extends substantially symmetrically about axis 104.
- a pumping assembly 106 is positioned about the drive shaft and is adapted to pump fluid from the pump inlet to the pump outlet.
- the pumping assembly includes a cylinder block 108 affixed to the drive shaft 102 and adapted to rotate therewith.
- a plurality of pistons 110 are adapted to reciprocate along linear paths of travel within the cylinder block 108.
- the swash plate assembly includes a standard wear plate 114 adapted to bear against the rotating pistons 110 and the angle of the swash plate assembly with respect to the drive shaft axis 104 determines the degree of reciprocation of the pistons 110 and therefore the displacement of the pump.
- a fluid actuated displacement control mechanism 16 is mechanically connected to the swash plate assembly 112 for controlling the displacement of the pumping assembly 106.
- the displacement control mechanism 16 includes a fluid passage for placing the mechanism in fluid communication with the reservoir 14 and includes a flow restriction which varies in response to the position of the mechanism.
- the displacement control mechanism includes a hollow control post 116 affixed to the pump housing 100, preferably by threaded engagement therewith.
- the hollow control post 116 has a generally cylindrical outer surface.
- a control piston 118 has a cylindrical wall defining a cylindrical inner surface 120 in sliding engagement with the cylindrical outer surface of the control post 116.
- the variable flow restriction is formed by a pair of tapered planar portions 124 on the outer surface of the control post. These tapered planar portions 124 are positioned so as to permit a variable degree of fluid communication between the hollow interior of the control post and the reservoir 14 while the displacement control mechanism controls the displacement of the pumping assembly.
- FIG. 4 shows a schematic representation of the sensor valve 54 of the present invention.
- Control signal 52 is applied to an inlet port 130 which leads to a central bore 132.
- An outlet port 134 leads to the displacement control mechanism 16.
- Another outlet port 136 leads to the reservoir 14.
- a spool 138 is positioned within the bore 132 and includes a pair of lands 140 and 142.
- a spring seat 144 is positioned against land 142 and retains spring 58 against a cap 146.
- the spool 138 is spring biased toward the port 130.
- the land 140 is of sufficient length to block the port 134.
- control signal 52 when the control signal 52 is of sufficient magnitude to depress the spring 58 against the cap 146 the control signal 52 will be placed in fluid communication with the displacement control mechanism 16. Conversely, when the spring bias applied to spool 138 by spring 58 exceeds the fluid bias applied by control signal 52 the spool will move toward port 130 and displacement control mechanism 16 will be placed in fluid communication with reservoir 14 by means of port 134, bore 132 and port 136.
- FIG. 5 shows a second embodiment of the hydraulic control circuit of the present invention which is identical to the embodiment shown in FIG. 1 with the exception that a second control valve 18a is utilized in addition to control valve 18 to provide fluid distribution to additional fluid actuated devices delivered by the same pump 12.
- the valve 18a is identical to the valve 18 with the exception that control port 50 and fixed orifice 44 have been removed so that the central passageway signal line 150 is connected in series between valve 18a and valve 18.
- a service line 152 places the inlet ports of valves 18a and 18 in parallel assuring fluid delivery to valve 18 even should one or both of the plungers in valve 18a be placed in an operating position.
- the principles of operation of this system are identical to that shown in FIG. 1.
- FIG. 6 shows a graphic representation of a third embodiment of the hydraulic control system of the present invention in which the control valve 18 is replaced by a control valve 160 in which a plurality of control plungers 162 and 164 are connected in tandem, as opposed to the parallel configuration shown in valve 18.
- fluid will be supplied to plunger 162 only through variable restriction 166.
- plunger 162 will receive no operating fluid.
- This type of arrangement is useful only in situations where the fluid actuated device supplied by plunger 164 has a much higher priority in the circuit than that supplied by plunger 162.
- the operation of the system shown in FIG. 6 is identical to that shown in FIG. 1.
- a hydraulic control system which is capable of controlling the distribution of fluid to a plurality of fluid actuated devices in a highly efficient and responsive manner.
- This system is not subject to signal reversals as a result of gravitational forces acting on the fluid actuated devices since there is no feedback from the load.
- the system requires the use of only a single control line to the pump.
- the control valve utilized in the system develops a control signal for the pump which is responsive to the position of the individual valve plungers.
- the displacement control mechanism for the pump further improves the responsiveness of the system. Since this system requires relatively simple and inexpensive modifications to existing control systems, it may be easily manufactured.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Reciprocating Pumps (AREA)
- Fluid-Pressure Circuits (AREA)
- Control Of Positive-Displacement Pumps (AREA)
Abstract
Description
Claims (22)
Priority Applications (14)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US05/910,726 US4197705A (en) | 1978-05-30 | 1978-05-30 | Hydraulic control system |
GB7915039A GB2021818B (en) | 1978-05-30 | 1979-05-01 | Hydraulic control system |
DE19792918708 DE2918708A1 (en) | 1978-05-30 | 1979-05-09 | HYDRAULIC CONTROL SYSTEM |
CA327,329A CA1095810A (en) | 1978-05-30 | 1979-05-10 | Hydraulic control system |
JP5757079A JPS54156202A (en) | 1978-05-30 | 1979-05-10 | Hydraulic controller |
IT22863/79A IT1114264B (en) | 1978-05-30 | 1979-05-21 | HYDRAULIC CONTROL SYSTEM |
NZ20279679A NZ202796A (en) | 1978-05-30 | 1979-05-22 | Control valve for hydraulic system |
NZ190516A NZ190516A (en) | 1978-05-30 | 1979-05-22 | Hydraulic control system for flow of fluid to a fluid actuated device |
AU47519/79A AU526907B2 (en) | 1978-05-30 | 1979-05-29 | Hydraulic control system |
SE7904673A SE439956B (en) | 1978-05-30 | 1979-05-29 | HYDRAULREGLERSYSTEM |
BR7903347A BR7903347A (en) | 1978-05-30 | 1979-05-29 | HYDRAULIC CONTROL SYSTEM, PERFECTING IN CONTROL VALVE AND VARIABLE DISPLACEMENT PUMP |
FR7914379A FR2427488B1 (en) | 1978-05-30 | 1979-05-29 | VARIABLE FLOW PUMP HYDRAULIC CONTROL SYSTEM |
CA360,220A CA1100016A (en) | 1978-05-30 | 1980-09-12 | Hydraulic control system |
CA360,219A CA1096270A (en) | 1978-05-30 | 1980-09-12 | Hydraulic control system |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US05/910,726 US4197705A (en) | 1978-05-30 | 1978-05-30 | Hydraulic control system |
Publications (1)
Publication Number | Publication Date |
---|---|
US4197705A true US4197705A (en) | 1980-04-15 |
Family
ID=25429245
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US05/910,726 Expired - Lifetime US4197705A (en) | 1978-05-30 | 1978-05-30 | Hydraulic control system |
Country Status (11)
Country | Link |
---|---|
US (1) | US4197705A (en) |
JP (1) | JPS54156202A (en) |
AU (1) | AU526907B2 (en) |
BR (1) | BR7903347A (en) |
CA (2) | CA1095810A (en) |
DE (1) | DE2918708A1 (en) |
FR (1) | FR2427488B1 (en) |
GB (1) | GB2021818B (en) |
IT (1) | IT1114264B (en) |
NZ (1) | NZ190516A (en) |
SE (1) | SE439956B (en) |
Cited By (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0056514A2 (en) * | 1981-01-16 | 1982-07-28 | General Signal Corporation | Hydraulic control system |
US4399886A (en) * | 1980-12-09 | 1983-08-23 | Sundstrand Corporation | Controls for variable displacement motor and motors |
US4479349A (en) * | 1981-11-19 | 1984-10-30 | General Signal Corporation | Hydraulic control system |
US4554991A (en) * | 1984-02-23 | 1985-11-26 | Mud Hog Corporation | Auxiliary hydraulic drive system for road graders and the like |
US4949805A (en) * | 1988-07-27 | 1990-08-21 | Clark Equipment Company | Electrically controlled auxiliary hydraulic system for a skid steer loader |
US5454223A (en) * | 1993-05-28 | 1995-10-03 | Dana Corporation | Hydraulic load sensing system with poppet valve having an orifice therein |
US5873244A (en) * | 1997-11-21 | 1999-02-23 | Caterpillar Inc. | Positive flow control system |
US5924509A (en) * | 1997-03-19 | 1999-07-20 | Caterpillar Paving Products Inc. | Traction control apparatus and method for a hydrostatically driven work machine |
EP1302663A1 (en) * | 2001-10-15 | 2003-04-16 | HEILMEIER & WEINLEIN Fabrik für Oel-Hydraulik GmbH & Co. KG | Electro-hydraulic motor pump unit and check valve unit |
US20060242955A1 (en) * | 2005-04-19 | 2006-11-02 | Clark Equipment Company | Hydraulic system with piston pump and open center valve |
US20080017022A1 (en) * | 2004-03-18 | 2008-01-24 | Kobelco Construction Machinery Co., Ltd. | Hydraulic control system for working machine |
CN103557153A (en) * | 2013-11-20 | 2014-02-05 | 沈阳工业大学 | Electric-hydraulic proportional displacement regulating mechanism of axial plunger hydraulic pump |
CN111911381A (en) * | 2020-07-26 | 2020-11-10 | 中国航发贵州红林航空动力控制科技有限公司 | Nozzle differential pressure valve mechanism with damping piston |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE4020325C2 (en) * | 1990-06-26 | 1995-01-05 | Hydrokraft Gmbh | Control device for adjustable hydraulic pumps |
CN115013275B (en) * | 2022-05-31 | 2024-03-08 | 江苏大学流体机械温岭研究院 | Load-sensitive digital axial plunger pump with active valve flow distribution and working method thereof |
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US3777492A (en) * | 1971-02-17 | 1973-12-11 | Dowty Technical Dev Ltd | Hydraulic apparatus including variable delivery pumps |
US3788077A (en) * | 1972-07-13 | 1974-01-29 | Borg Warner | Open center control of variable pumps |
US4067193A (en) * | 1976-11-22 | 1978-01-10 | Caterpillar Tractor Co. | Combined hydrostatic transmission implement system |
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GB1262488A (en) * | 1968-06-04 | 1972-02-02 | Dowty Technical Dev Ltd | Hydraulic apparatus for including variable-delivery pumps |
DE1728270A1 (en) * | 1968-09-19 | 1972-03-09 | Bosch Gmbh Robert | Hydraulic control system |
DE1943356A1 (en) * | 1969-08-26 | 1971-03-18 | Rauch Fa Constantin | Device for controlling adjustable axial piston pumps |
JPS4942082A (en) * | 1972-08-28 | 1974-04-20 | ||
US3809501A (en) * | 1973-01-08 | 1974-05-07 | Gen Signal Corp | Hydraulic load sensitive system |
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1978
- 1978-05-30 US US05/910,726 patent/US4197705A/en not_active Expired - Lifetime
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1979
- 1979-05-01 GB GB7915039A patent/GB2021818B/en not_active Expired
- 1979-05-09 DE DE19792918708 patent/DE2918708A1/en not_active Ceased
- 1979-05-10 JP JP5757079A patent/JPS54156202A/en active Pending
- 1979-05-10 CA CA327,329A patent/CA1095810A/en not_active Expired
- 1979-05-21 IT IT22863/79A patent/IT1114264B/en active
- 1979-05-22 NZ NZ190516A patent/NZ190516A/en unknown
- 1979-05-29 FR FR7914379A patent/FR2427488B1/en not_active Expired
- 1979-05-29 BR BR7903347A patent/BR7903347A/en unknown
- 1979-05-29 SE SE7904673A patent/SE439956B/en not_active IP Right Cessation
- 1979-05-29 AU AU47519/79A patent/AU526907B2/en not_active Ceased
-
1980
- 1980-09-12 CA CA360,219A patent/CA1096270A/en not_active Expired
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Publication number | Priority date | Publication date | Assignee | Title |
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US3777492A (en) * | 1971-02-17 | 1973-12-11 | Dowty Technical Dev Ltd | Hydraulic apparatus including variable delivery pumps |
US3788077A (en) * | 1972-07-13 | 1974-01-29 | Borg Warner | Open center control of variable pumps |
US4067193A (en) * | 1976-11-22 | 1978-01-10 | Caterpillar Tractor Co. | Combined hydrostatic transmission implement system |
Cited By (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4399886A (en) * | 1980-12-09 | 1983-08-23 | Sundstrand Corporation | Controls for variable displacement motor and motors |
EP0056514A3 (en) * | 1981-01-16 | 1982-08-04 | General Signal Corporation | Hydraulic control system |
US4408453A (en) * | 1981-01-16 | 1983-10-11 | General Signal Corporation | Hydraulic control system |
EP0056514A2 (en) * | 1981-01-16 | 1982-07-28 | General Signal Corporation | Hydraulic control system |
US4479349A (en) * | 1981-11-19 | 1984-10-30 | General Signal Corporation | Hydraulic control system |
US4554991A (en) * | 1984-02-23 | 1985-11-26 | Mud Hog Corporation | Auxiliary hydraulic drive system for road graders and the like |
US4949805A (en) * | 1988-07-27 | 1990-08-21 | Clark Equipment Company | Electrically controlled auxiliary hydraulic system for a skid steer loader |
US5454223A (en) * | 1993-05-28 | 1995-10-03 | Dana Corporation | Hydraulic load sensing system with poppet valve having an orifice therein |
US5924509A (en) * | 1997-03-19 | 1999-07-20 | Caterpillar Paving Products Inc. | Traction control apparatus and method for a hydrostatically driven work machine |
US5873244A (en) * | 1997-11-21 | 1999-02-23 | Caterpillar Inc. | Positive flow control system |
EP1302663A1 (en) * | 2001-10-15 | 2003-04-16 | HEILMEIER & WEINLEIN Fabrik für Oel-Hydraulik GmbH & Co. KG | Electro-hydraulic motor pump unit and check valve unit |
US6739129B2 (en) | 2001-10-15 | 2004-05-25 | Heilmeier & Weinlein Fabrik F. Oel-Hydraulik Gmbh & Co. Kg | Electrohydraulic motor pump aggregate, attachable element and pressure limiting valve |
US20080017022A1 (en) * | 2004-03-18 | 2008-01-24 | Kobelco Construction Machinery Co., Ltd. | Hydraulic control system for working machine |
US20060242955A1 (en) * | 2005-04-19 | 2006-11-02 | Clark Equipment Company | Hydraulic system with piston pump and open center valve |
CN103557153A (en) * | 2013-11-20 | 2014-02-05 | 沈阳工业大学 | Electric-hydraulic proportional displacement regulating mechanism of axial plunger hydraulic pump |
CN103557153B (en) * | 2013-11-20 | 2016-01-20 | 沈阳工业大学 | The electric-hydraulic proportion discharge capacity controlling mechanism of axial plunger hydraulic pump |
CN111911381A (en) * | 2020-07-26 | 2020-11-10 | 中国航发贵州红林航空动力控制科技有限公司 | Nozzle differential pressure valve mechanism with damping piston |
Also Published As
Publication number | Publication date |
---|---|
IT7922863A0 (en) | 1979-05-21 |
SE7904673L (en) | 1979-12-01 |
AU526907B2 (en) | 1983-02-03 |
FR2427488A1 (en) | 1979-12-28 |
FR2427488B1 (en) | 1986-05-16 |
CA1095810A (en) | 1981-02-17 |
DE2918708A1 (en) | 1979-12-06 |
IT1114264B (en) | 1986-01-27 |
GB2021818B (en) | 1982-11-17 |
GB2021818A (en) | 1979-12-05 |
CA1096270A (en) | 1981-02-24 |
NZ190516A (en) | 1985-04-30 |
JPS54156202A (en) | 1979-12-10 |
BR7903347A (en) | 1979-12-11 |
AU4751979A (en) | 1979-12-06 |
SE439956B (en) | 1985-07-08 |
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